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 $FD50/64848:   Initialise System Constants

Jump from <A HREF="ROMFCE2.HTM">$FCF5</A>, <A HREF="ROMFF87.HTM">$FF87</A>:

FD50: A9 00     <A HREF="BLDA.HTM">LDA</A> #$00
FD52: A8        <A HREF="BTAY.HTM">TAY</A>

Jump from $FD5D:

FD53: 99 02 00  <A HREF="BSTA.HTM">STA</A> <A HREF="ZP02.HTM">$0002</A>,Y   ; Unused
FD56: 99 00 02  <A HREF="BSTA.HTM">STA</A> <A HREF="ZP0200.HTM">$0200</A>,Y   ; BASIC Input Buffer (Input Line from Screen)
FD59: 99 00 03  <A HREF="BSTA.HTM">STA</A> <A HREF="ZP0300.HTM">$0300</A>,Y   ; Vector: BASIC Error Message
FD5C: C8        <A HREF="BINY.HTM">INY</A>
FD5D: D0 F4     <A HREF="BBNE.HTM">BNE</A> $FD53
FD5F: A2 3C     <A HREF="BLDX.HTM">LDX</A> #$3C
FD61: A0 03     <A HREF="BLDY.HTM">LDY</A> #$03
FD63: 86 B2     <A HREF="BSTX.HTM">STX</A> <A HREF="ZPB2.HTM">$B2</A>       ; Pointer: Start Address of Tape Buffer
FD65: 84 B3     <A HREF="BSTY.HTM">STY</A> <A HREF="ZPB2.HTM">$B3</A>       ; Pointer: Start Address of Tape Buffer
FD67: A8        <A HREF="BTAY.HTM">TAY</A>
FD68: A9 03     <A HREF="BLDA.HTM">LDA</A> #$03
FD6A: 85 C2     <A HREF="BSTA.HTM">STA</A> <A HREF="ZPC1.HTM">$C2</A>       ; Start Address for LOAD and Cassette Write

Jump from $FD86:

FD6C: E6 C2     <A HREF="BINC.HTM">INC</A> <A HREF="ZPC1.HTM">$C2</A>       ; Start Address for LOAD and Cassette Write

Jump from $FD84:

FD6E: B1 C1     <A HREF="BLDA.HTM">LDA</A> (<A HREF="ZPC1.HTM">$C1</A>),Y   ; Start Address for LOAD and Cassette Write
FD70: AA        <A HREF="BTAX.HTM">TAX</A>
FD71: A9 55     <A HREF="BLDA.HTM">LDA</A> #$55
FD73: 91 C1     <A HREF="BSTA.HTM">STA</A> (<A HREF="ZPC1.HTM">$C1</A>),Y   ; Start Address for LOAD and Cassette Write
FD75: D1 C1     <A HREF="BCMP.HTM">CMP</A> (<A HREF="ZPC1.HTM">$C1</A>),Y   ; Start Address for LOAD and Cassette Write
FD77: D0 0F     <A HREF="BBNE.HTM">BNE</A> $FD88
FD79: 2A        <A HREF="BROL.HTM">ROL</A>
FD7A: 91 C1     <A HREF="BSTA.HTM">STA</A> (<A HREF="ZPC1.HTM">$C1</A>),Y   ; Start Address for LOAD and Cassette Write
FD7C: D1 C1     <A HREF="BCMP.HTM">CMP</A> (<A HREF="ZPC1.HTM">$C1</A>),Y   ; Start Address for LOAD and Cassette Write
FD7E: D0 08     <A HREF="BBNE.HTM">BNE</A> $FD88
FD80: 8A        <A HREF="BTXA.HTM">TXA</A>
FD81: 91 C1     <A HREF="BSTA.HTM">STA</A> (<A HREF="ZPC1.HTM">$C1</A>),Y   ; Start Address for LOAD and Cassette Write
FD83: C8        <A HREF="BINY.HTM">INY</A>
FD84: D0 E8     <A HREF="BBNE.HTM">BNE</A> $FD6E
FD86: F0 E4     <A HREF="BBEQ.HTM">BEQ</A> $FD6C

Jump from $FD77, $FD7E:

FD88: 98        <A HREF="BTYA.HTM">TYA</A>
FD89: AA        <A HREF="BTAX.HTM">TAX</A>
FD8A: A4 C2     <A HREF="BLDY.HTM">LDY</A> <A HREF="ZPC1.HTM">$C2</A>       ; Start Address for LOAD and Cassette Write
FD8C: 18        <A HREF="BCLC.HTM">CLC</A>
FD8D: 20 2D FE  <A HREF="BJSR.HTM">JSR</A> <A HREF="ROMFE25.HTM">$FE2D</A>     ; Read / Set Top of Memory
FD90: A9 08     <A HREF="BLDA.HTM">LDA</A> #$08
FD92: 8D 82 02  <A HREF="BSTA.HTM">STA</A> <A HREF="ZP0281.HTM">$0282</A>     ; Pointer: Bottom of Memory for Operating System
FD95: A9 04     <A HREF="BLDA.HTM">LDA</A> #$04
FD97: 8D 88 02  <A HREF="BSTA.HTM">STA</A> <A HREF="ZP0288.HTM">$0288</A>     ; High Byte of Screen Memory Address
FD9A: 60        <A HREF="BRTS.HTM">RTS</A>

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Kernal-Reference:

 LDA $FD93,X : <A HREF="ROMFCB8.HTM">$FCBD</A>

 LDA $FD94,X : <A HREF="ROMFCB8.HTM">$FCC3</A>

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